Babe, my advice is pay for the seat. Your ds1 will be fine with the plane-seat belt, but for your ds2 ask them to give you the infant seat belt which loops through your belt, then around him (on your lap) for take off and landing. Then sit him on his own seat for the rest. You'll appreciate the space!!

For a short trip I wouldn't bother with the car seat. I've never used one in all of our travels, Singapore, London etc, and just see it as another thing to carry around!

My DS is so used to plane travel now, he gets complimented by other passengers coz he knows the 'drill'....

Have fun on your holiday.... Although you should be coming to jersey for a potential white Christmas lol xx